CN105422824A - Planet-carrier for an epicyclic gearing and epicyclic gearing provided with such a planet-carrier - Google Patents

Abstract

A planet-carrier (5) for an epicyclic gearing (1) having an annular structure (9), provided with a coupling portion (10) for being connected to a rotating member or to a static structure in an angularly fixed manner, and a ring (15) that is coaxial to the annular structure (9) along a transmission axis (3) and consists of a plurality of plate-shaped sectors (16) and of a plurality of attachment sectors (17), alternating with one another about the transmission axis (3); the plate-shaped sectors (16) lie on a plane (P) orthogonal to the transmission axis (3) and are fixed with respect to pairs of pins (19), which protrude in opposite directions from the plate-shaped sectors (16) and are adapted to carry respective planet gears (2); each of the attachment sectors (17) is fastened to the structure (9) by a corresponding pair of arms (31), which converge with each other towards the ring (15) and are elastically deformable so as to allow a relative movement between the ring (15) and the structure (9) under load.

Description

Planet carrier and the planetary gear system being provided with this planet carrier of planetary gear system

Technical field

The present invention relates to a kind of planet carrier for planetary gear system, particularly relate to a kind of planet carrier for aerospace applications, following description will relate to aerospace applications, but the present invention will not lose any versatility.

Background technique

As everyone knows, planetary gear system is widely used in aeroengine field, for transmission and transfer power between turbogenerator (there is high speed and low moment of torsion) and at least one propulsion element (there is high moment of torsion and low speed), because planetary gear system keeps weight and volume to reduce for these functions of execution very effectively simultaneously.

Beyond aviation industry, particularly there is similar design solution in wind-driven generator construction applications, and wherein, gearing performs the function of multiplier speed (speedmultiplier), instead of performs the function of retarder.

Except naturally saving in weight, especially feel for reducing in the new aeroengine structure (structure of the driving turbofan of such as non-immediate and open rotor) that consumes and pollute the volume that needs to reduce gear as much as possible what studying.In these structures, in fact planetary gear system is formed with turbogenerator entirety, wherein, the diameter envelope (diametralenvelope) of gearing for regulating the geometrical shape of the passage of the flowing of air or combustion gas, thus affects the efficiency of turbogenerator fatefully.

One for realizing these gearings favourable solution is considered to use the planet carrier with annular slab, the two group planetary pinions of this annular slab support arrangement on the relative side of plate.Particularly, planetary pin is separately provided with bearing, sells and give prominence to from plate on the relative direction of the axis being parallel to gearing.Such as, the solution of the type is known from claimant EP2339208 and WO2013065024 under one's name.

In the field of the solution of the type, need consumingly to seek load is evenly distributed along multiple torque transmission paths in gearing.This is evenly distributed is the necessary condition realizing the lightest weight of gearing and minimum overall volume.In fact, the uncertainty of the uneven and estimation skewness of possible load diatibution independent of the effective stress state of the assembly of gearing in the design of the assembly (cogwheel, bearing etc.) of gearing and operating overload factor when determining size, cause all parts excessive, even cause in fact being subject to the excessive of stress small parts.

Load diatibution inequality is substantially due to following factor:

-planetary gear system (also according to adopt concrete solution) becomes hyperstatic, torque transmission paths thus inevitably bear larger stress, wherein, provides larger rigidity;

-relative to nominal assembling and geometric condition, gearing inevitably has and causes each assembly to produce the instrument error of relative displacement and assembly error and tolerance with respect to the assembly of design planning, thus produces overload;

-can asymmetric from outside imposed load/displacement at the connection joining part place of gearing.

Usually, the minimized primary solutions of the first two factor that can make to point out above can be classified as follows:

-be intended to the disparity (asymmetric) along each torque transmission paths is minimized and introduce orientable element or flexible member with the solution of support planetary gears, orientable element or flexible member are such as (wherein, the pin energy local buckling of support planetary gears) of so-called flexible pin-type; And

-be intended to compensate asymmetric solution by making the rigidity in each torque transmission paths suitably balance.

The solution described in WO2013065024 effectively reduces load diatibution inequality by introducing radial joint thus supports this plate.But this solution needs relatively a large amount of assemblies and joint through frayed on the parts that couple of rubbing, and therefore this solution has lower reliability.

Therefore, preferably the solution that planet carrier does not have joint is directly designed.

Given this, in the solution described in patent EP2072863 and EP2072858, planet carrier advantageously makes single.

But the planet carrier of this latter two solution has sizable asymmetric relative to two groups of planetary symmetry planes, and does not consider that the flexible member introducing flexible pin-type is to support these planetary pinions.

Particularly, single-piece planet carrier supports two groups of planetary plates by the attachment by being connected to running shaft or static structure and consists of the arm or beam that plate are connected to attachment.These arms are arranged essentially parallel to the axis of gearing, and are positioned in circumferential direction in the space between planetary pinion.Therefore, moment of torsion is passed to above-mentioned arm from plate, and is passed to attachment from arm.

This structure is not gratifying, because the intrinsic distortion of arm and deforming trend under loads attachment between by the spreadable life is transferred to plate.Therefore, plate bears the bending moment applied at each tie point by arm.The bending axis of the pin of support planetary gears that causes of the plate produced by the bending moment of these local tilts, thus produce load at two groups of planetary one and undesirable unbalance between another, i.e. skewness, and produce the undesirable reaction stress in the join domain now between pin and plate.

In order to limit by the distortion of attachment cause unbalance, thus in plate, keep the stress that produced by bending moment, plate must be made has significant axial width.But this size design makes planet carrier to gearing structure and assembly error and tolerance especially responsive (such as, planetary position is with respect to the displacement of the position of design planning).Uneven and the significant overload of further load diatibution on planetary pinion is caused to the sensitivity of error and tolerance.

Therefore, the solution described in EP2072863 and EP2072858 can not compensate the asymmetric of planet carrier thus limit load skewness effectively.

In addition, the concrete solution proposed in EP2072863 and EP2072858 does not allow to make planetary supporting pin and plate make one, because if do like this, and the bearing that can not assemble planetary pinion He be associated.Therefore, these solutions needs have and have high coupling of interfering between carried pins and plate, to avoid the material risk of the wearing and tearing of parts when contacting.

Summary of the invention

The object of this invention is to provide a kind of planet carrier for planetary gear system, this planet carrier can solve the problem in simple and cheap mode.

According to the present invention, provide a kind of planet carrier for planetary gear system, this planet carrier comprises:

-ring structure, this ring structure comprises and described planet carrier is connected to rotating member in angled fixing mode or to static structure;

-ring part, this ring part is coaxial with described ring structure along transmission axis, and described ring part forms by around described transmission axis multiple tabular section alternating with each other and multiple attachment section; Described slab region section is positioned at in the plane of described transmission axis vertical take-off;

-multiple pin, described multiple pin is fixed relative to described tabular section, described multiple pin is outstanding along respective axis from described tabular section in an opposite direction, and described multiple pin is parallel and relative to described transmission eccentric axis, and described multiple pin is suitable for carrying respective planetary pinion;

-connection set, is fixed to described attachment section by described structure;

Wherein, described connection set comprises a pair arm of the correspondence for each attachment section, and arm relative to each other draws in towards described ring part and is resiliently deformable to allow the relative movement under loads between described ring part and described structure.

Accompanying drawing explanation

Now, describe the present invention with reference to the accompanying drawings, accompanying drawing shows non-limiting embodiment, in accompanying drawing:

Fig. 1 is the stereogram of the planetary gear system of the preferred implementation be equipped with according to planet carrier of the present invention;

Fig. 2 is the cross section of the gearing in Fig. 1 along meridian line cutting plane;

Fig. 3 is the stereogram of the planet carrier in Fig. 1 and Fig. 2;

Fig. 4 is the enlarged view of the details of planet carrier in Fig. 3; And

Fig. 5 is the different stereogram of the planet carrier in Fig. 3.

Embodiment

With reference to figure 1, reference number 1 represents the planetary gear system comprising multiple planetary pinion 2, multiple planetary pinion is arranged around axis 3, and multiple planetary pinion is around paralleling to the axis 3 and rotate relative to the respective axis 4 of this eccentric axis, and multiple planetary pinion is supported by planet carrier 5.

Planetary pinion 2 is arranged to formation two group 2a and 2b, these two groups are symmetrical relative to the plane P orthogonal with axis 3, and outwards engage with two internal tooths of ring gear 6 and inwardly engage with two sun gears 7, these two sun gears are coaxial and fixing relative to axle 8.Advantageously, sun gear 7 and axle 8 make one.According to unshowned modification, the tooth of ring gear 6 and/or two sun gears 7 substitutes by with two of the planetary pinion 2 single teeth organizing axial length that 2a and 2b engage enough.

Preferably, but and not exclusively, each group of 2a and 2b has three planetary pinions 2, with make axis 4 each other uniform with 120 ° around axis 3.

Advantageously, planet carrier 5 by single block (namely, the body made by single) limit and comprise ring structure 9, ring structure is defined for the extraction/insert member of mated gear and has couplings 10, and couplings is defined for the coupling with angled means of fixation, planet carrier 5 being connected to unshowned component (such as output driving shaft) or static structure.In the instantiation illustrated, couplings 10 is by being designed by screw or the bolton flange limit to rotating member or static structure.Alternately, couplings 10 is limited by hole spline or axle spline.

In the instantiation illustrated, couplings 10 is positioned at relative to ring gear 6 and the larger radius of ring structure 9 and from structure 9 towards plane P displacement.According to unshowned modification, couplings 10 is positioned at the sidepiece of gearing 1 along axis 3 with the larger or less radius relative to ring gear 6 and ring structure 9.

With reference to figure 3, planet carrier 5 also comprises ring part 15, and ring part is coaxial with structure 9 along axis 3, and is made up of multiple sections 16 alternating with each other in circumferential direction and multiple section 17.Section 16 limits by being positioned in plane P and the tabular section ending at flexible thin wall portion 18 on circumferentially direction, and this section engages with section 17.Such as, section 16 has the thickness (usual thickness is 5mm to 7mm) being less than 10mm: these one-tenth-value thickness 1/10s are generally used for having the gearing of two groups of planetary 15MW, often organizes planetary pinion and all has three planetary pinions.Meanwhile, section 17 is more more not flexible than section 16.

As shown in Figures 1 and 2, planetary pinion 2 supports by via the pin of respective bearing 20 (preferably being limited by rolling bearing) or axle 19.Each pin 19 preferably makes one with corresponding section 16, with the part making pin 19 form planet carrier 5.

Pin 19 and section 16 is used to form overall solution better, because: this solution decreases the quantity of assembly; Reduce on the risk of interference fit joint wearing and tearing and wear surface and produce the possibility of fatigue crack; Be convenient to due to the concrete shape of ring structure 9 assemble planetary pinion, as will be hereafter described better.But according to unshowned modification, pin 19 can be separated with the parts be such as fastened on by interference fit on each section 16.

As seen in Figure 3, section 16 preferably includes respective spine 21, and axially and project upwards in the side relative with part 18, and this spine defines axial shoulder in spine, and the inner ring 22 of bearing 20 places (Fig. 2) against axial shoulder.Each inner ring 22 is all installed in the outer cylindrical surface 24 of corresponding pin 19, and bearing 20 does not preferably have outer ring simultaneously: in other words, as visible at Fig. 2, the outer raceway of the rolling element 25 of bearing 20 is limited by the internal surface 26 of planetary pinion 2.Preferably, rolling element 25 is spherical roller bearings, is spill thus the tooth of planetary pinion 2 can be made by pin 19 distortion under loads to separate to make raceway.

As mentioned above, pin 19 is axially outstanding and along axis 4 toward each other from the two sides of section 16.Preferably, pin 19 is defined through the respective axial passage 27 that connection set (not shown) engages, and connection set makes spine 21 be locked into axially against inner ring 22.

Preferably, the tooth of planetary pinion 2 is the cylindricalitys with straight-tooth.

Planetary group of 2a be arranged in relative to plane P be provided with structure 9 side on.According to planning and determining the shape and size of structure 9 to stay for assembling along respective axis 4 on pin 19 and removing enough radial clearances of planetary group of 2a based on the diameter of planetary pinion 2 and the position of axis 4.In order to this object and referring to figs. 2 and 5, for each pin 19, structure 9 comprises corresponding section 28, and this section is hollowed out to form groove 29 by radial direction, and this groove to be aimed at pin 19 and the size and dimension of this groove is designed to allow the axial passage of planetary pinion 2 by structure 9 along axis 4.And for each section 28, structure 9 comprises respective strengthening rib 30, strengthening rib is outstanding to limit radial deformation from described section 28 outward radial.

According to unshowned modification, structure 9 is parts of separating with ring part 15 and is fastened on ring part between the erecting stage of gearing 1.In this case and/or when pin 19 is the parts of the separation be assemblied on section 16, usually, for installation planetary group of 2a there is not interference problem, structure 9 thus can have towards axis 3 shrink shape (such as bell-shaped) be directly connected for running shaft.

As seen in Figure 4, for each section 17, planet carrier 5 comprises corresponding a pair link arm or beam 31, this is arranged in the space between two adjacent planetary group of 2a to link arm or beam, and section 17 is connected with structure 9, to transmit the shearing (tangential force) between ring part 15 and structure 9, thus transmitting torque.

Arm or beam 31 comprise corresponding intermediate portion 32, and intermediate portion draws in toward each other and is preferably straight, and arm or beam comprise corresponding end 33 and 34, the connection of end difference qualifying part 32 and structure 9 and section 17.

Arm 31 forms the quadrilateral of trapezoidal shape with two parts 35 together with 36, and quadrilateral is tangential or circumference substantially, and limits the trapezoidal longer end and the shorter end.In preferred implementation with illustrating described here, planet carrier 5 makes single, and wherein, part 35 forms a part for structure 9 and replaces around axis 3 and section 28, and part 36 forms the part of section 17 respectively.

According to unshowned modification, the quadrilateral pointed out above and structure are separated and/or are separated with ring part 15: in these cases, part 35 by screw or bolton to structure 9 and/or part 35 by screw or bolton to section 17.

Two arms 31 of each quadrilateral are provided with the elastic bending deflection larger relative to part 35 and 36, quadrilateral thus be out of shape under loads.Particularly, the resiliently deformable of arm 31 can make relative movement between ring part 15 and structure 9 under loads, and avoids bending moment to be passed to ring part 15 from structure 9.As can be seen here, due to this resiliently deformable, ring part 15 trends towards independent of structure 9 and deflects, and makes structure 9 distortion under loads that section 16 can not be made to bend.

In other words, allow section 17 under arm 31 this is configured in the impact of the shear action that moment of torsion produces and therefore allow ring part 15 accurately to rotate around axis 3.If the arm of often pair of arm 31 is parallel to each other and/or substituted by single arm, as in known technology, result will be can not by the structure of ring part 15 with bending " isolation " of structure 9, because the bending meeting of structure is passed to ring part 15 unchangeably, this is without any benefit.

As from accompanying drawing, arm 31 draws in towards ring part 15 instead of towards structure 9: if arm 31 draws in towards structure 9, and the analog representation carried out goes out distortion will be passed to section 17 from structure 9, and even produces the actual amplification of these distortion.

Bending " isolation " of the ring part 15 illustrated more than considering and structure 9, section 16 must only support tangential shear action.As can be seen here, from the viewpoint of design, by only considering that these tangential shear action design the size of ring part 15, and the thickness of section 16 therefore can be reduced significantly relative to the known solution being equipped with overall planet carrier.

Particularly, as mentioned above, the thickness s on the axial direction of part 18 be it is said " thin ", and namely rotary inertia I is (wherein, the I=h*s under minimum ³/ 12) cross section has thickness s in accordance with following geometric proportion and width h:h>5s.

When there is manufacture and assembly error, flexural rigidity is the determination element of the overload quantized on planetary pinion 2, as can be seen here, the ring part 15 being equipped with very thin section 16 ensures the low sensitivity of instrument error and inherently therefore to the high tolerance of instrument error, and there is no need to adopt the flexible pin-type solution for pin 19.

In fact, machining tolerance and assembly error cause deviating from the operational condition of the best, the especially tangential displacement of planetary pinion 2, namely around the rotation of the bending axis orthogonal with axis 4.Unbalance by the torque path that is tending towards causing organizing between 2a and 2b of this displacement.Instead, in the present case, section 16 is automatically out of shape and therefore absorbs these errors and recover acceptable operational condition due to their low flexural rigidity.

In addition, due to error and tolerance, in use, the junction point between pin 19 and section 16 produces moment M, and therefore produces the change of the normal load transmitted by pin 19.In order to limit the overload relative to normal load, moment M must be little as much as possible significantly.The flexibility (that is, low flexural rigidity) of ring part 15 is larger, and moment M will be less.

In the present case, by arranging extremely low flexural rigidity K (namely, by reducing the thickness of section 16), the operation of gearing 1 and reliability are not undermined, still guarantee the high tolerance to instrument error: particularly, can with the value (application without the need to any measurement additionally for wind turbine has replaced the load distribution factor of more than 20%) the load distribution factor between planetary pinion 2 being remained in about 5%.Therefore, claimed solution achieves the result with higher performance relative to known solution.

And, tooth due to planetary pinion 2 does not need to process overload and therefore can be dimensioned to what be used for maximum stress the size being less than known solution, and because ring part 15 is at the thickness s of the reduction at section 16 place, so gearing is low weight.

Be back to Fig. 2 and Fig. 4, as mentioned above, part 35 and 36 is preferably hardening for bending with moment of torsion relative to tangential axis.Particularly, arm 31 limits corresponding virtual articulated section or resilient hinge at end 33 and 34 place to the hinge axes be a little tending towards under loads by substantially radial relative to axis 3 that couples of part 35 and 36.In other words, the quadrilateral that ring part 15 is connected with structure 9 is virtual hinged quadrilateral, and wherein, the hinge connection of real quadrilateral is substituted by the region of local deformation.

The shape and size (such as: the relative distance of length, radial thickness, width, arm 31 and tilt angle) of each deformable quadrilateral are such as determined according to plan by suitable simulation, to guarantee load being uniformly distributed in each torque transmission paths.

Particularly, each quadrilateral is make the distortion of ring part 15 independent of the distortion of structure 9 by design structure, as mentioned above, and makes the distribution optimization of rigidity in planet carrier 5, and guarantees the feasibility from technical standpoint planet carrier 5.

In the mode of execution preferably illustrated, each section 17 comprises coplanar with section 16 and has the wall 40 of thickness s identical with section 16 substantially.Meanwhile, part 36 is made up of two ribs 41 and 42, and two ribs are arranged along the outer annular rim of ring part 15 and give prominence to from wall 40 in an opposite direction.Particularly, rib 42 is relative with structure 9 about plane P.

Each section 17 also comprises rib 43 and two cross ribs 44, rib 43 is arranged along the inner annular rim of ring part 15 and gives prominence to from wall 40 on the direction identical with rib 42, and two cross ribs are given prominence to from wall 40 and the end of rib 42 are connected to the end of rib 43 on the direction identical with 43 with rib 42.

Therefore, for each section 17, rib 42,43 and 44 defines a chamber, and the bottom in this chamber is limited by wall 40.The flexural rigidity of part 36 can keep the relative position of two ends 34 constant substantially during using gearing 1.Meanwhile, rib 44 and 43 limits stiffener to avoid part 36 around the moment of torsion of the tangential axis of part 36.

With reference to figure 1, Fig. 2 and Fig. 5, the part 35 of structure 9 comprises: wall 45, and this wall is orthogonal with axis 3 and axially in the face of section 17; And comprise multiple rib 46, on the relative side that multiple rib is arranged in the wall 45 of ring part 15 and the weight be configured to without the need to losing planet carrier 5 just can torsionally make part 35 become strengthens.Part 35 and section 28 are combined at flange 10 place by bell-shaped portion 47, and flange arrangement becomes the axial end portion around ring gear 6, the axial end portion encirclement group 2a of ring gear and arm 31.

By description above, give planet carrier 5 by arm 31 and the advantage therefore brought to the operation of gearing 1 is obvious.Particularly, as described in detail above, the flexibility of arm 31 prevents local bending moments to be passed to ring part 15 from structure 9, thus the design of this ring part can ignore these bending moments, and therefore there is for adopting the solution of the known technology of all-in-one-piece planet carrier processed the thickness s of the reduction for section 16.The reduction of thickness s and then make ring part 15 have high flexibility, in the tangential direction of high flexibility auto-compensation between two that belong to different group 2a and 2b coaxial planetary pinions by constructing or assembly error and by any relative displacement caused by machining tolerance.There is low-down flexural rigidity and also mean the overload reduced in region that pin 19 is connected with section 16.

And, the solution being described in the drawings and illustrating allow to make rigidity in planet carrier 5 relative to the distribution optimization of plane P so that load diatibution inequality is decreased to minimum.

Meanwhile, two arms 31 avoid the device using joint between structure 9 and ring part 15, because this reducing the quantity of wearing and tearing and assembly and adding reliability relative to the known solution being equipped with this device.

Under any circumstance, the solution of employing does not hinder the flexible pin-type solution used about pin 19, thus improves the compensation to structure or assembly error and machining tolerance further.

And, make single of planet carrier 5 one-tenth not only reduce the quantity of parts that are to be manufactured and that assemble, and the risk of the damage allowing reduction to cause due to the fretting fatigue in the contact coupled components of bearing cyclic loading.

Although planet carrier 5 is made into single, the assembling of gearing 1 is relatively simple, especially owing to using groove 29 and the gear with straight-tooth, and their permissions axially assembling/remove the group 2a's of planetary pinion 2.

And two sun gears 7 make single, to reduce the radial volume of gearing 1 with axle 8.This structure of sun gear 7 bears the unbalance of the torsional stiffness of two torque transmission paths effectively, and the feature of above-described planet carrier 5 allows compensation this unbalance.Meanwhile, the compact radial dimension of sun gear achieves higher velocity ratio for set volume, or achieves less volume for set velocity ratio.

Based on mentioned above, be also obvious to other secondary advantages of those skilled in the art.

By it is evident that when not deviating from scope of the present invention defined in the appended claims above, amendment or modification can be applied to planet carrier 5.

Particularly, the size of arm 31, relative distance and tilt angle, as size and the geometrical shape of part 35 and 36, can be different from pointed out by the mode of example size, relative distance and tilt angle.

And each section 17 can by being fastened to structure 9 more than the arm of two elastically deformables.

And, the structure of gearing 1 can be a structure of the ring gear (so-called star configuration) with static planet carrier and rotation, there is the planet carrier of rotation and a structure of static ring gear (so-called planetary structural), or there is the structure of all elements (so-called differential configuration) of rotation.

In addition, as mentioned above, unshowned replacement scheme can have part 10 in relevant position and/or part 47, and/or has the shape being different from the mode of execution illustrated.Particularly, can make these assemblies with relative to ring gear 6 and structure 9 larger or less radius arrange along the lateral end place of axis 3 at gearing 1.

Claims (13)

1. the planet carrier for planetary gear system (1) (5), described planet carrier (5) comprising:

-ring structure (9), described ring structure comprises couplings (10) so that described planet carrier (5) is connected to rotating member or static structure in angled fixing mode;

-ring part (15), described ring part is coaxial with described ring structure (9) along transmission axis (3), and described ring part forms by around described transmission axis (3) multiple tabular sections (16) alternating with each other and multiple attachment section (17); Described tabular section (16) is positioned in the plane (P) orthogonal with described transmission axis (3);

-multiple pin (19), described multiple pin is fixing relative to described tabular section (16), described multiple pin is outstanding along respective axis (4) from described tabular section (16) in an opposite direction, described multiple pin is parallel and eccentric relative to described transmission axis (3), and described multiple pin is suitable for carrying respective planetary pinion (2);

-connection set, described ring structure (9) is fixed to described attachment section (17) by described connection set;

It is characterized in that, described connection set comprises a pair arm (31) of the correspondence for each described attachment section (17), arm described in a pair towards described ring part (15) relative to each other draw in and can resiliently deformable to allow relative movement under loads between described ring part (15) and described ring structure (9).

2. planet carrier according to claim 1, it is characterized in that, described arm has end (33,34), described end limits the edge with base part (35,36), described base part is tangential or circumference relative to described transmission axis (3), and described base part is firmer than described arm (31).

3. planet carrier according to claim 2, it is characterized in that, for each described attachment section (17), the trapezoidal shape quadrilateral that described connection set forms by arm described in a pair (31) and described base part (35,36) limits.

4. planet carrier according to claim 3, it is characterized in that, each described trapezoidal shape quadrilateral is sized to and limits four virtual articulated sections in the described end of described arm (31) by the hinge axes radial relative to described transmission axis (3) under loads.

5. planet carrier according to claim 2, is characterized in that, each described attachment section (17) comprising:

-wall (40), described wall and described tabular section (16) coplanar;

-external rib (41,42), described external rib limits one in described base part (36), and described external rib is arranged along the outer annular rim of described ring part (15) and gives prominence to from described wall (40) in the axial direction.

6. planet carrier according to claim 5, is characterized in that, each described attachment section (17) comprises two external ribs (41,42), and these two external ribs are given prominence to from described wall (40) on relative axial direction.

7. planet carrier according to claim 5, is characterized in that, each described attachment section (17) also comprises:

-internal rib (43), described internal rib is arranged along the inner annular rim of described ring part (15) and gives prominence to from described wall (40) in the axial direction; And

-two cross ribs (44), described cross rib is given prominence to from described wall (40) on the direction identical with described internal rib (43), and described cross rib makes the end of described external rib (42) be connected with the end of described internal rib (43).

8. planet carrier according to claim 1, is characterized in that, described ring part (15), described ring structure (9) and described connection set form a part for single piece body.

9. planet carrier according to claim 8, is characterized in that, described pin (19) also forms a part for described single piece body.

10. planet carrier according to claim 1, it is characterized in that, described ring structure (9) comprises multiple hollow section (28), described multiple hollow section and described connection set are around described transmission axis (3) alternately, and described multiple hollow section limits respective groove (29), described groove is axially aimed at described pin (19), and the shape and size of described groove are designed to allow corresponding planetary pinion axially through described ring structure (9).

11. planet carriers according to claim 10, it is characterized in that, described ring structure (9) comprises the strengthening rib (30) of the correspondence for each described hollow section (28), and described strengthening rib from described hollow section (28) radially outwardly.

12. 1 kinds of planetary gear system, comprising:

-according to planet carrier in any one of the preceding claims wherein (5);

-multiple planetary pinion (2), described multiple planetary pinion is mounted in the upper rotation of described pin (19) and limits relative to two symmetrical groups (2a, 2b) of described plane (P);

-ring gear (6), described ring gear has at least one internal tooth engaged with described planetary pinion (2);

-at least one sun gear (7), at least one sun gear described can rotate around described transmission axis (3) and engage with described planetary pinion (2).

13. planetary gear system according to claim 12, is characterized in that, described planetary gear system comprises axle (8), and described axle is coaxial with described sun gear (7) along described transmission axis (3); Described sun gear (7) and described axle (8) form a part for single piece body.